Now showing items 1-8 of 8

    • A succinct data structure for self-indexing ternary relations 

      Álvarez García, Sandra; De Bernardo Roca, Guillermo; Rodríguez Brisaboa, Nieves; Navarro, Gonzalo (Elsevier BV, 2016-10-27)
      [Abstract] The representation of binary relations has been intensively studied and many different theoretical and practical representations have been proposed to answer the usual queries in multiple domains. However, ternary ...
    • Aggregated 2D range queries on clustered points 

      Bernardo Roca, Guillermo de; Konow, Bernardo; Navarro, Gonzalo; Rodríguez Brisaboa, Nieves; Seco, Diego (Elsevier Ltd, 2016-09)
      [Abstract] Efficient processing of aggregated range queries on two-dimensional grids is a common requirement in information retrieval and data mining systems, for example in Geographic Information Systems and OLAP cubes. ...
    • Efficient and Compact Representations of Some Non-canonical Prefix-Free Codes 

      Fariña, Antonio; Gagie, Travis; Manzini, Giovanni; Navarro, Gonzalo; Ordóñez, Alberto (Springer, 2016-09-21)
      [Abstract] For many kinds of prefix-free codes there are efficient and compact alternatives to the traditional tree-based representation. Since these put the codes into canonical form, however, they can only be used when ...
    • Efficient Representation of Multidimensional Data over Hierarchical Domains 

      Brisaboa, Nieves R.; Cerdeira Pena, Ana Belén; López López, Narciso; Navarro, Gonzalo; Penabad, Miguel R.; Silva Coira, Fernando (Springer, 2016-09-21)
      [Abstract] We consider the problem of representing multidimensional data where the domain of each dimension is organized hierarchically, and the queries require summary information at a different node in the hierarchy of ...
    • GraCT: A Grammar Based Compressed Representation of Trajectories 

      Brisaboa, Nieves R.; Gómez Brandón, Adrián; Navarro, Gonzalo; Paramá, José R. (Springer, 2016-09-21)
      [Abstract] We present a compressed data structure to store free trajectories of moving objects (ships over the sea, for example) allowing spatio-temporal queries. Our method, GraCT, uses a k2k2 -tree to store the absolute ...
    • Grammar compressed sequences with rank/select support 

      Ordóñez, Alberto; Navarro, Gonzalo; Brisaboa, Nieves R. (Elsevier BV, 2016-10-14)
      [Abstract] Sequence representations supporting not only direct access to their symbols, but also rank/select operations, are a fundamental building block in many compressed data structures. Several recent applications need ...
    • Improved Compressed String Dictionaries 

      Brisaboa, Nieves R.; Cerdeira Pena, Ana Belén; De Bernardo Roca, Guillermo; Navarro, Gonzalo (ACM, 2019-11-03)
      [Abstract] We introduce a new family of compressed data structures to efficiently store and query large string dictionaries in main memory. Our main technique is a combination of hierarchical Front-coding with ideas from ...
    • Universal indexes for highly repetitive document collections 

      Claude, Francisco; Fariña, Antonio; Martínez Prieto, Miguel A.; Navarro, Gonzalo (Elsevier Ltd, 2016-11)
      [Abstract] Indexing highly repetitive collections has become a relevant problem with the emergence of large repositories of versioned documents, among other applications. These collections may reach huge sizes, but are ...